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Scott Dennstaedt, PhD

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Scott Dennstaedt, PhD last won the day on January 12 2022

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  1. It was just an overshooting top within some convection they happened to stumble into. You can see it here on the visible satellite image. That turret is creating a pretty good shadow to the NNW.
  2. Even more scary is that most microbursts are not from supercell thunderstorms...they are usually from benign-appearing cells that have little or no lightning. I just wrote an article for FLYING magazine that should appear in the March issue that discusses this and the concerns you should have when flying around any areas of convection.
  3. The temperature in the area at FL410 were nearly -60°C. The PIREP may have been reporting the total air temperature, not the static air temperature. Once the static air temperature gets to be -40°C or colder, liquid water cannot exist. No matter how pristine the drop is, it will freeze. Supercooled liquid water is very rare below -35°C. This is a clear case of high ice water content and not supercooled liquid water. So that begs the question...what is icing from an advisory perspective. Supercooled liquid water? Induction? Carburetor? High ice water content? There are no advisories issued for the latter three.
  4. I don't usually make too big of a stink when I see an advisory or forecast go off the rails...but this is one of those that I just can't withhold a comment... Earlier today I noticed a center weather advisory (CWA) issued by the Jax CWSU for severe ice between FL380 and 410. Huh? What? Must be an error. Even the AWC parser didn't pick up the altitudes for this. That CWA was likely issued upon receipt of this urgent PIREP from an Embraer EMB-505 Phenom 300. Moreover, there was also a convective SIGMET in the area that implies severe ice by definition. You don't need both of these. Lack of coordination between the CWSU and the AWC. At a temperature approaching -60°C, it's not likely a supercooled liquid water (airframe icing) issue even with convection nearby. Given the temps at that altitude it's more likely high ice water content. The report was made not far outside of the strongest echoes, rather than right within them. Ugh!
  5. I don't use FF, so can't really help. Suggest looking at the FF pilots guide for info.
  6. The problem is that most of these pilots don’t know it is stupid since they were never taught otherwise.
  7. Yes! Having trained thousands of pilots over the last 25 years, the lack of knowledge is likely the biggest reason pilots make poor preflight and inflight decisions. I am not saying that experience is useless, but often risk is addictive. Pilots often gain the wrong experience and use previous successes as the reason for their next go decision. Just because that 3,000 ft stratocumulus deck that they climbed through over the last 10 times resulted in little or no ice accretion, doesn’t mean it’ll be the same on the 11th try. Turns out that the air was much cleaner on the 11th go which resulted in SLD in the climb nearly killing a pilot. He reached out to me to learn why. He learned a ton and now has knowledge to make a better decision-experience alone did not serve him well. Knowledge combined with experience (applied knowledge) is extremely valuable.
  8. That’s correct. Anything with a high radius of curvature allows for efficient ice accretion. So ice accretions themselves make efficient ice collectors.
  9. I do. I wrote this blog post a while back, but it still has relevance for this topic today.
  10. KGAI 272156Z AUTO VRB04KT 1 1/4SM BR OVC002 11/11 A2945 RMK AO2 SLP987 T01060106 KGAI 272128Z AUTO 18003KT 1 1/4SM BR OVC002 11/11 A2945 RMK AO2 KGAI 272121Z AUTO 14006KT 3/4SM BR OVC002 10/10 A2945 RMK AO2
  11. When I was based in Baltimore, I did a lot of flights to GAI including dozens of instrument approaches in actual IMC. Always said that it was just a matter of time before someone hit those power lines. I just don’t see how anyone survived this, much less two people and that nobody on the surface was injured or killed.
  12. You will hear ATC use "extreme" as a level of icing intensity, but there's no such definition for it. Severe is the maximum since it defines the situation where the ice protection system on the aircraft cannot keep up with the amount of ice that is accreting. Extreme turbulence...yes...extreme icing...no. On the various icing analyses and forecasts, the term heavy is used instead of severe. Severe is reserved for how the airplane reacts to the meteorological conditions, not the meteorological conditions themselves. If you are a student of history, an update to the AIM on February 9, 2012 in section 7-1-21 added Heavy to the way pilots should report ice...they said, This change addresses the change to the icing intensity definitions, quantifiable icing rates, and an updated replacement for current terminology. It would also help satisfy NTSB Safety recommendations A­96­51 and ­060. The interesting thing is that they also removed Trace as a pilot-reported intensity. Here's what it ended up looking like... 1. Light. The rate of ice accumulation requires occasional cycling of manual deicing systems** to minimize ice accumulations on the airframe. A representative accumulation rate for reference purposes is 1/4 inch to one inch (0.6 to 2.5 cm) per hour (See TBL 7-1-7) on the unprotected part of the outer wing. The pilot should consider exiting the condition. 2. Moderate. The rate of ice accumulation requires frequent cycling of manual deicing systems** to minimize ice accumulations on the airframe. A representative accumulation rate for reference purposes is 1 to 3 inches (2.5 to 7.5 cm) per hour (See TBL 7-1-7) on the unprotected part of the outer wing. The pilot should consider exiting the condition as soon as possible. 3. Heavy.  The rate of ice accumulation requires maximum use of the ice protection systems to minimize ice accumulations on the airframe. A representative accumulation rate for reference purposes is more than 3 inches (7.5 cm) per hour (See TBL 7-1-7) on the unprotected part of the outer wing. Immediate exit from the conditions should be considered. 4.  Severe. The rate of ice accumulation is such that ice protection systems fail to remove the accumulation of ice and ice accumulates in locations not normally prone to icing, such as areas aft of protected surfaces and any other areas identified by the manufacturer. Immediate exit from the condition is necessary. But in the very next update to the AIM, they abandoned this approach and went back to the way it is today. Ugh!
  13. Thanks! Personally when I want to really see all the details of the radar depiction I use the Radarscope app. That way I can see the velocity data as well as the Dual Pol data. Gust fronts, outflow boundaries, microbursts, etc. all show up nicely on this app. Caught this microburst from the TDWR near Charlotte the other day with some pulse-type convection in the area. https://www.instagram.com/reel/Cg2rbsqM9i0/
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